A conventional plasma processing apparatus is disclosed in, for example, Japanese Patent Laid-open Publication No. 2005-100931 (Patent Document 1). The plasma processing apparatus described therein includes: a plasma generating chamber which accommodates a target substrate therein; an antenna which generates an electromagnetic field driven by microwave; a top plate which seals an opening portion of the plasma generating chamber; and a tapered protruding portion or recess portion formed at a bottom surface side of the top plate.
The plasma processing apparatus having the above-described configuration is capable of forming an optimal resonance region under any conditions by successively varying the thickness of the top plate in a diametric direction. As a result, it is mentioned in Patent Document 1 that a stable plasma generation is enabled.
Patent Document 1: Japanese Patent Laid-open Publication No. 2005-100931